Fabric collecting means for power looms

ABSTRACT

A power loom wherein the fabric is trained over a fixedly mounted first driven collecting beam, thereupon over a second collecting beam which is movable toward and away from the first collecting beam, and finally over one of two additional beams which support the second collecting beam. The other additional beam is mounted on two levers which are pivotable by mechanical or fluid-operated means to move the second collecting beam toward or away from the first collecting beam so as to permit the passage of fabric knots through the nip of the collecting beams and the nips between the second collecting beam and each of the additional beams when the other additional beam is moved away from the first collecting beam. The breast beam is urged against the fabric by a fluid-operated motor to compensate for slackening of the fabric in response to beating up of filling threads by the reed.

United States Patent [1 1 Bassing et a1.

[ FABRIC COLLECTING MEANS FOR POWER LOOMS [75] Inventors: Friedrich Wilhelm Bassing; Gerhard Hofmann, both of Hamburg, Germany [73] Assignee: Alia-Laval Bergedorfer Eisenwerke GmbH, Hamburg, Germany [22] Filed: May 17, 1974 [21] Appl. No.: 470,505

[30] Foreign Application Priority Data May 22, 1973 Germany 2325.908

52 US. cl..... 139/308; 66/149 YR [51] D03D 49/20 [58] Field of Search., 139/304, 307-311,

[56] References Cited UNITED STATES PATENTS 1,629,849 5/1927 Todd 139/291 R 2,888,955 6/1959 Kondo 139/99 3,050,972 8/1962 Noe t. 139/307 X 3,698,446 10/1972 Miller et a1. 139/308 3,752,378 8/1973 Scheffel 139/99 UX 3,753,452 8/1973 Zebley 139/311 3,828,827 8/1974 Witt et al 139/304 Oct. 7, 1975 FOREIGN PATENTS OR APPLICATIONS Primary Examiner.1ames Kee Chi Attorney, Agent, or Firm-Michael S. Striker [5 7] ABSTRACT A power loom wherein the fabric is trained over a fixedly mounted first driven collecting beam, thereupon over a second collecting beam which is movable toward and away from the first collecting beam, and finally over one of two additional beams which support the second collecting beam. The other additional beam is mounted on two levers which are pivotable by mechanical or fluid-operated means to move the sec ond collecting beam toward or away from the first collecting beam so as to permit the passage of fabric knots through the nip of the collecting beams and the nips between the second collecting beam and each of the additional beams when the other additional beam is moved away from the first collecting beam. The breast beam is urged against the fabric by a fluidoperated motor to compensate for slackening of the fabric in response to beating up of filling threads by the reed.

23 Claims, 3 Drawing Figures US. Patent Oct. 7,1975 Sheet 1 of3 3,910,319

U.S. Patent Oct. 7,1975 Sheet 3 0f 3 3,910,319

Fig. 3

FABRIC COLLECTING MEANS FOR POWER LOOMS BACKGROUND OF THE INVENTION The present invention relates to power looms in general, and more particularly to improvements in means for collecting and transporting woven fabric downstream of the reed in a power loom.

It is already known to provide a power loom with a fabric collecting unit wherein a layer of fabric coming from the breast beam is trained over a first rolleror drum-shaped driven collecting beam, thereupon over a second collecting beam, and finally over one of two additional beams which serve as supports for the second beam. The first and second beams are driven to rotate in opposite directions. The additional beams of the collecting unit are rotatable in the machine frame about fixed axes and support the second beam in such position that the latter is out of contact with the first beam. The means for rotating the first and second beams of the collecting unit comprises a transmission or the like which rotates the first beam, and a train of gears between the shafts of the first and second beams. The fabric coming from the breast beam is fed directly to the periphery of the first beam in the collecting unit; therefore, such power looms cannot compensate for recurrent slackening of the fabric which develops in response to each forward stroke of the reed, i.e., while the reed beats up the last-introduced filling thread. Such action of the reed causes a slight forward shifting of the fabric when the result that the fabric slips rela tive to the periphery of the first beam in the collecting unit. In fact, the beating up often results in slippage of fabric with respect to each of the first two beams in the collecting unit. This interferes with uniformity of the fabric collecting action and hence with uniformity of thread distribution in the fabric. Additional problems arise when after insertion of a new warp those knots by which the new warp threads are connected to the previously woven fabric or a tying-on canvas have to pass through the collecting station.

On the other hand, uniformity of thread distribution is of great importance in many types of fabrics, for example, in foundrinier wires for use in paper making machines.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved fabric collecting unit for power looms which insures that the fabric is collected at a constant and uniform rate, even during travel of fabric knots through the collecting station.

Another object of the invention is to provide a novel and improved mounting or support structure for the second beam of the collecting unit in a power loom.

A further object of the invention is to provide novel and improved means which can automatically compensate for such shifting of woven fabric which takes place whenever the reed beats up a freshly introduced filling thread.

An additional object of the invention is to provide a novel and improved mounting for the breast beam bar in a power loom.

Still another object of the invention is to provide a power loom for the production of woven fabrics wherein the distribution of filling threads is moreiuniform than in fabrics when are produced in conventional power looms.

The invention is embodied in a power loom, and more particularly in a means for collecting woven fabric which is obtained by interweaving warp threads with filling threads. The collecting means comprises a first rotary collecting beam which is preferably rotatable about a fixed axis downstream of the breast beam or analogous compensating means, a second rotary collecting beam which is adjacent to and parallel with the first collecting beam, and first and second additional beams which support the second collecting beam and are parallel with the first collecting beam. The fabric is trained over the first collecting beam, thereupon over the second collecting beam, and finally over the first additional beam. The collecting means further comprises one or more step-down transmissions or analogous means for rotating the first and second collecting beams in opposite directions independent of the position and the movement of said second collecting beam relative to said first collecting beam to thereby advance the fabric toward the first additional beam, and means for moving at least one of the additional beams (for example, the second additional beam) sideways independently of the other additional beam in directions toward and away from the first collecting beam to thereby move the second collecting beam sideways with respect to the first collecting beam and to thus change the distance between the collecting beams of the fabric passing through the nip of the collecting beams.

The means for moving the one additional beam may comprise mechanical or fluid-operated means for maintaining the one additional beam in a position in which the latter urges the second collecting beam against the fabric in the nip of the collecting beams.

The means for moving said one additional beam may include means to maintain a predetermined pressure of said collecting beams upon the fabric passing through said nip.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The inproved power loom itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary schematic partly elevational and partly longitudinal vertical sectional view of a power loom which embodies one form of the invention;

FIG. 2 is a perspective view of the collecting station in the power loom of FIG. 1; and

FIG. 3 is a partly diagrammatic fragmentary longitudinal vertical sectional view of a modified power loom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a portion of a power loom wherein an upright frame member or wall F supports a rotary crankshaft 50 for an arm 51 which reciprocates a sword 52 for a reed 3 through which pass the warp threads I and 2. The woven fabric 4 is pulled by three collecting beams 9, 10, ll of which the beam 10 is mounted, shifted and driven in accordance with a feature of the present invention. The sley 53 is shown in a position in which the last-introduced filling thread (not specifically shown) is about to be beaten up by the reed 3.

The first or foremost collecting beam 9 is preceded by a breast beam over which the fabric 4 passes and which is pivotable in the frame member F, as at 54. The means for biasing the breast beam 5 counterclockwise, as viewed in FIG. 1, comprises a fluid-operated motor 8 having a piston 7 and a piston rod 6 which is articulately connected to a supporting plate 55 for the shaft of the breast beam 5. The shaft of the beam 5 can be mounted in two plates (see the portion of a second supporting plate 55') and the biasing means can comprise two motors 8, one for each of the plates 55, 55. The motor 8 is articulately connected to the frame member F and its right-hand chamber is connected to a source of pressurized fluid. Such fluid is maintained at a given constant pressure so that the plates 55 and 55 can pivot at 54 whenever the fabric 4 is shifted forwardly in response to a beating-up stroke of the reed 3. It will be noted that the breast beam 5 constitutes a means for compensating for intermittent slackening of the fabric 4 in response to beating up of successive filling threads.

The fabric 4 is trained over the collecting beams 9, I0, I I but not over an additional beam 12 which cooperates with the additional beam 11 to urge the beam 10 against the beam 9, i.e., against the fabric 4 in the nip of the beams 9, 10. The take-off structure which col lects the fabric 4 in the form of a roll downstream of the beam 11 is not shown in the drawing.

The beams 9, 11 and 12 can be supported at the ends well as at one or more intermediate points. The beam 10 is preferably supported only by the beams 11, 12 because the major part of its peripheral surface (about three-fourths of such surface) is surrounded by the fabric 4. The beams 9, 11 and 12 will be supported at, as well as intermediate, their ends if the power loom is to produce a fabric of considerable width. FIG. 2 shows that the beams 9 and 11 are journalled intermediate their ends, as at 9A and 11A.

The beam 12 is rotatably mounted on two one-armed levers or carriers 13 which are pivoted to the frame member F, as at 14, and the free ends of which carry coupling pins 15 for reciprocable feed screws 16. Each feed screw 16 meshes with a worm wheel 17a rotatable in bearings 17A and mating with a worm 1717 on a worm shaft 18. When the shafts 18 are driven by a motor, not shown, the carriers 13 change the distance between the beams 12, 9 and thus change the position of the beam 10 relative to the beams 9, 11 and 12. In normal operation, the carriers 13 are biased clockwise so as to urge the beam 12 against the beam 10 and to thereby urge the beam 10 against the beams 9 and 11. In this way, the beam 10 is rotatably held in a position of exact parallelism with the beams 9, 11 and 12.

FIG. 2 shows that the left-hand end of the beam 9 is connected to a first output shaft 29 of a step-down transmission 31 by a coupling 56. The output shaft 29 rotates in a bearing 30 which is mounted in the case of the transmission 31. A second output shaft 32 of the transmission 31 is rotatable in a bearing 33 of the transmission case and serves to drive the beam 10 through the medium of a parallel crank drive 34 which allows the beam 10 to move sideways in response to shifting of the beam 12. The details of the drive 34 are known; this drive can be replaced by a mechanism including two Cardan joints or the like. The illustrated drive 34 is preferred at this time because it takes up less space than a plurality of universal joints. The gear train in the case of the transmission 31 drives the output shafts 29, 32 in such a way that the peripheral speed of the beam 10 matches the peripheral speed of the beam 9. Thus, if the diameters of the beams 9, 10 are identical, the output shaft 32 is driven at the same angular speed of the output shaft 29. The drive 34 insures that the beam 10 is driven independent of the position and the movement of the beam 12 (i.e., in response to movement of the axis of the beam 12 toward or away from the axis of the beam 9), even if the beam 10 is moved away from the beam 9 so that the beams 9, 10 define a gap for the passage of fabric 4 and of knots or analogous protubcrances which project from the general plane of the fabric.

The input member 131 of the transmission 31 can be driven by a discrete prime mover, not shown, or it may receive torque from the main crankshaft of the power loom. For example, the input member 131 of the transmission 31 can be driven by the crankshaft 50 through the medium of a chain drive and a reducing gearing. This insures that the peripheral speed of the beams 9, l0 varies in synchronism with the speed of other moving parts of the power loom.

It is also possible to vary the speed of the transmission 31 in response to changes in tension of warp threads 1, 2 and/or fabric 4. FIG. 1 shows a detector which monitors the tension of warp threads and/or fabric 4 and serves to regulate the speed of output shafts 29, 32 in response to changes in such tension. The detector can include a spring-biased roller or the like which bears against the warp threads and whose posi tion is indicative of the tension. The details of the operative connection (see the line 61 in FIG. 1) between the detector 60 and transmission 31 form no part of the invention.

When the reed 3 of FIG. 1 is actuated to beat up a freshly introduced filling thread, it causes the fabric 4 between the parts 3 and 5 to move forwardly. This displacement of the fabric 4, known as banging, causes intermittent slackening of the fabric which passes around the breast beam 5. The slack is taken up by fluid pressure in the right-hand chamber of the cylinder 8 so that the breast beam 5 oscillates in rhythm with the banging of fabric, either in response to leftward shifting of the reed 3 or in response to increasing tension of the fabric when the reed 3 moves in a direction to the right, as viewed in FIG. 1. The just described oscillatory movements of the breast beam 5 in response to alternating slackening and tensioning of the fabric 4 insure that the fabric is not lifted off the beams 9, 10 and is taken off at a constant rate without any slippage.

In order to facilitate the passage of knots through the collecting means including the beams 911, the worm shaft 18 of FIG. 1 is rotated to move the feed screws 16 in a direction to the right, as viewed in FIG. 1, so that the carriers 13 pivot counterclockwise and the beam 12 moves away from the beam 9. This causes the beam 10 to move away from and to define with the beam 9 a small clearance for unobstructed passage of the knots. Such knots thereupon pass between the beams 10, 12 and 10, 11 by lifting the beam 10 above and away from the beam 11. When the knots advance beyond the nip of the beams 10 and 11, the worm shaft 18 is rotated in the opposite direction so that the carriers 13 pivot clockwise and the beam 12 urges the beam 10 toward FIG. 3 shows a portion of a second power'loom wherein the mechanical means 16-18 for pivoting the carriers 13 of FlG. 1 is replaced by a fluid-operated system including at least one cylinder 21 which is articulately connected with the frame member F (not shown), as at 21a, and has a piston '20 Coupled to the free end of a carrier 13 by a piston rod- 19"andpi n 15.

Theright-hand chamber 21/) of the'cylinder 21 communicates with a conduit 23:: whichis Connected to the outlet of a hydraulic pump 23. The latter is "driven by an electric motor 22 and draws hydraulic fluid (e.g.,

oil) from a tank 28. The con'duit23u contains a check valve 24 which is installedupstream of an accumulator 25 serving as a pressure fluid reservoir, and 'thisaccumulator is installed upstream of a-pressure gauge 26. An adjustable pressure relief valve 27 between the gauge 26 and cylinder 21 opens when'the fluid pressure in the conduit 23:: rises to a predetermined value and the valve 27 then allows pressurized fluid to flow from as the pressure of fluid in the chamber 21b exceeds the preselected value whereby the fluid which is-supplied by pump 23 flows to the tank 28 through the return line28.

When the'knots enter'the "nip of the beams 9 and 10, they move'the beam slightly away from the beam 9 so that the pressure offluid in'the chamber 21b rises because the piston moves'in a directionto the right. The fluid which is thereby expelled from'the chamber 21b flows into'the tank 28 via valve 27and line 28. This automatically compensates for increased pressure between the beams 9 and 10 during passage of knots.

The beam 10 moves nearer to the beam 9 as soon as the knots advance beyond the nipi-of the beams 9and 10. The force with which the beam 1.0 thereupon bears against the fabric 4 is again'the same' asbefore,'as long as the setting of the valve 27 remains unchanged. 1"

The operation of the system 19-28 is analogous when the knots pass between'the beams 10, .1'2'and thereupon between the beams 10, 11.: If desired, the valve 27 can be adjusted to open in response to a lower fluid pressure during passage of knots between the beams 9-10, 10-12 and 101 1. This facilitates the passage of knots through the collecting station.

The novel features of the power loom which embodies the structure of FIGS. 12 or FIG. 3 contribute to uniform distribution of filling threads. This is achieved by preventing slippage of the fabric during travel through the collecting station.

The drive 34 (or an analogous drive) insures that the peripheral speed of the beam 10 remains unchanged (i.e., that it invariably equals the peripheral speed of the beam 9) in spite of the fact that the beam 10 changes its position with respect to the other beams at the collecting station. It will be noted that the beams 9, 10 are driven to rotate in opposite directions. The drive 34 insures that the peripheral speeds of the beams 9, 10

the

are identical even if the magnitude of force with which the beamTO bears against the fabric 4 in the nip of the beams 9, 10 varies within a rather'wide range.

I The improved power loom is susceptible of many additional modifications without departing from the spirit of the invention. For example, the pivotable carrier or carriers 13 for the beam 12 can be replaced bycarrier means wherein or with which the beam 12 is reciprocable in directions toward and'aw'ay from the beam 9. Moreover, the feed-screw or screws 16 (or the piston rod or piston rods 19) can be coupled directly to the ends of the shaft for the beam 12 (i.e., the carrier or carriers 13 can be omitted altogether). Still further, the breast beam 5 can be mounted for reciprocatory (rather than pivotal) movement along a straight or arcuate path. At the present time, a pivotal mounting for the beamS and/or 12 is preferred owing to its simpliclty. j

1f the power loom is designed for the production of a relatively wide fabric, a drive 34 (or an analogous drive) can be connected with each end of the shaft for the beam 10. See the coupling 56' in FIG. 2; this coupling forms part of a second transmission which drives the righthand ends of shafts for the beams 9 and 10. 'The two stepdowntransmissions 31 are driven in synchronism and each thereof transmits torque to a different end of the shaft for the beam 9 and to a differend end of the shaft for the beam 10. Each of the transmissions can be installed in its entirety in a discrete housing which is filled with oil or another lubricant.

Withoutfurther analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be; comprehended within the meaning and range of equivalence of the claims. I

.What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. Ina power loom, means for collecting woven fabric which is, obtained by interweaving warp threads with filling threads, comprising a first rotary collecting beam; a second rotary collecting beam adjacentto and parallel with said first. collecting beam and forming a nip therewith; firstand second additional beams parallel with said firstcollecting beam and supporting said second-collecting beam, thefabric being trained over said first collecting beam, passed through said nip of said first and second collecting beams, thereupon over said second collecting beam and finally over said first additional beam; means for rotating said first and second collecting beams in opposite directions to thereby advance said fabric towards said first additional beam, said means for rotating including a drive for rotating said second collecting beam independent of the position and the movement of said second collecting beam with respect to said first collecting beam; and means for moving one of said additional beams independently of the other of said additional beams in'directions toward and away from said first collecting beam to thereby move said second collecting beam with respect to said first collecting beam and to thus change the distance between said collecting beams.

2. The structure of claim 1, wherein said means for moving said one additional beam comprises means for maintaining said one additional beam in a position in which the latter urges said second collecting beam against the fabric in the nip of said collecting beams.

3. The structure of claim 2, wherein said means for moving said one additional beam comprises means to maintain a predetermined pressure of said collecting beams upon the fabric passing through said nip.

4. The structure of claim 1, wherein said means for moving comprises a device for pivoting said one additional beam about an axis which is parallel to the axis of said first collecting beam.

5. The structure of claim 1, wherein said means for rotating comprises a transmission having a first rotary output member for rotating said first collecting beam at a predetermined peripheral speed and a second rotary output member, and a drive receiving torque from said second output member and arranged to rotate said second collecting beam at said predetermined peripheral speed.

6. The structure of claim 5, wherein said transmission is a step-down transmission and said first collecting beam is rotatable about a fixed axis.

7. The structure of claim 5, wherein said drive is a parallel crank drive.

8. The structure of claim 5, wherein said drive comprises a plurality of universal joints.

9. The structure of claim 1, wherein said second collecting beam extends with an uninterrupted cylindrical peripheral surface over the whole working width.

10. The structure of claim 1, further comprising means for rotatably supporting said first collecting beam and/or at least one of said additional beams intermediate the ends thereof.

11. The structure of claim 1, wherein said means for rotating includes discrete drives for each end of said second collecting beam.

12. The structure of claim I, wherein said means for moving comprises at least one carrier rotatably supporting said one additional beam, a frame, means securing said carrier to said frame for pivotal movement about an axis which is parallel to the axes of said beams, and means for pivoting said carrier.

13. The structure of claim 12, wherein said means for pivoting said carrier comprises at least one fluidoperated motor.

14. The structure of claim 13, wherein said motor includes a cylinder having a piston reciprocable in said cylinder and a piston rod connected to said piston, one of said cylinder and said piston rod being articulately connected to said carrier and the other one being connected to said frame.

15. The structure of claim 14, wherein said cylinder has a chamber for reception of pressurized fluid which moves said piston in a direction to move said one additional beam toward said first collecting beam, said means for pivoting said carrier further comprising a source of pressurized fluid connected with said chamber and a pressure relief valve interposed between said source and said chamber to maintain the fluid pressure in said chamber within a predetermined range.

16. The structure of claim 1, further comprising a reed, means for moving said reed so that the latter beats up successive filling threads upstream of said first collecting beam, as considered in the direction of movement of the fabric, with attendant intermittent slackening of the fabric, and means for compensating for said slackening of the fabric upstream of said first collecting beam.

17. The structure of claim 16, wherein said compensating means comprises a mobile breast beam and means for biasing said breast beam against the fabric.

18. The structure as defined in claim 17, further comprising a pivotable support for said breast beam, said means for biasing comprising a device for pivoting said support so that said breast beam bears against the fabric between said reed and said first collecting beam.

19. The structure of claim 18, wherein said device for pivoting said support comprises a fluid-operated motor having a piston operatively connected with said support, a plenum chamber adjacent to said piston, and

means for maintaining the pressure in said chamber' within a predetermined range so that said piston tends to pivot said support with a constant force whereby the support causes said breast beam to bear against the fabric.

20. The structure of claim 1, wherein said means for moving said one additional beam comprises a plurality of fluid-operated motors and means for maintaining the fluid in each of said motors at identical pressure.

21. The structure of claim 1, wherein said means for rotating said first and second collecting beams comprise a rotary drive member and a plurality of transmissions each having an input member receiving torque from said drive member.

- 22. The structure of claim 1, further comprising means for monitoring the tension of warp threads and means for changing the speed of said rotating means response to changes in said tension.

23. The structure of claim 1, wherein said means for rotating comprises a plurality of synchronized transmissions having output elements arranged to rotate said collecting beams. 

1. In a power loom, means for collecting woven fabric which is obtained by interweaving warp threads with filling threads, comprising a first rotary collecting beam; a second rotary collecting beam adjacent to and parallel with said first collecting beam and forming a nip therewith; first and second additional beams parallel with said first collecting beam and supporting said second collecting beam, the fabric being trained over said first collecting beam, passed through said nip of said first and second collecting beams, thereupon over said second collecting beam and finally over said first additional beam; means for rotating said first and second collecting beams in opposite directions to thereby advance said fabric towards said first additional beam, said means for rotating including a drive for rotating said second collecting beam independent of the position and the movement of said second collecting beam with respect to said first collecting beam; and means for moving one of said additional beams independently of the other of said additional beams in directions toward and away from said first collecting beam to thereby move said second collecting beam with respect to said first collecting beam and to thus change the distance between said collecting beams.
 2. The structure of claim 1, wherein said means for moving said one additional beam comprises means for maintaining said one additional beam in a position in which the latter urges said second collecting beam against the fabric in the nip of said collecting beams.
 3. The structure of claim 2, wherein said means for moving said one additional beam comprises means to maintain a predetermined pressure of said collecting beams upon the fabric passing through said nip.
 4. The structure of claim 1, wherein said means for moving comprises a device for pivoting said one additional beam about an axis which is parallel to the axis of said first collecting beam.
 5. The structure of claim 1, wherein said means for rotating comprises a transmission having a first rotary output member for rotating said first collecting beam at a predetermined peripheral speed and a second rotary output member, and a drive receiving torque from said second output member and arranged to rotate said second collecting beam at said predetermined peripheral speed.
 6. The structure of claim 5, wherein said transmission is a step-down transmission and said first collecting beam is rotatable about a fixed axis.
 7. The structure of claim 5, wherein said drive is a parallel crank drive.
 8. The structure of claim 5, wherein said drive comprises a plurality of universal joints.
 9. The structure of claim 1, wherein said second collecting beam extends with an uninterrupted cylindrical peripheral surface over the whole working width.
 10. The structure of claim 1, further comprising means for rotatably supporting said first collecting beam and/or at least one of said additional beams intermediate the Ends thereof.
 11. The structure of claim 1, wherein said means for rotating includes discrete drives for each end of said second collecting beam.
 12. The structure of claim 1, wherein said means for moving comprises at least one carrier rotatably supporting said one additional beam, a frame, means securing said carrier to said frame for pivotal movement about an axis which is parallel to the axes of said beams, and means for pivoting said carrier.
 13. The structure of claim 12, wherein said means for pivoting said carrier comprises at least one fluid-operated motor.
 14. The structure of claim 13, wherein said motor includes a cylinder having a piston reciprocable in said cylinder and a piston rod connected to said piston, one of said cylinder and said piston rod being articulately connected to said carrier and the other one being connected to said frame.
 15. The structure of claim 14, wherein said cylinder has a chamber for reception of pressurized fluid which moves said piston in a direction to move said one additional beam toward said first collecting beam, said means for pivoting said carrier further comprising a source of pressurized fluid connected with said chamber and a pressure relief valve interposed between said source and said chamber to maintain the fluid pressure in said chamber within a predetermined range.
 16. The structure of claim 1, further comprising a reed, means for moving said reed so that the latter beats up successive filling threads upstream of said first collecting beam, as considered in the direction of movement of the fabric, with attendant intermittent slackening of the fabric, and means for compensating for said slackening of the fabric upstream of said first collecting beam.
 17. The structure of claim 16, wherein said compensating means comprises a mobile breast beam and means for biasing said breast beam against the fabric.
 18. The structure as defined in claim 17, further comprising a pivotable support for said breast beam, said means for biasing comprising a device for pivoting said support so that said breast beam bears against the fabric between said reed and said first collecting beam.
 19. The structure of claim 18, wherein said device for pivoting said support comprises a fluid-operated motor having a piston operatively connected with said support, a plenum chamber adjacent to said piston, and means for maintaining the pressure in said chamber within a predetermined range so that said piston tends to pivot said support with a constant force whereby the support causes said breast beam to bear against the fabric.
 20. The structure of claim 1, wherein said means for moving said one additional beam comprises a plurality of fluid-operated motors and means for maintaining the fluid in each of said motors at identical pressure.
 21. The structure of claim 1, wherein said means for rotating said first and second collecting beams comprise a rotary drive member and a plurality of transmissions each having an input member receiving torque from said drive member.
 22. The structure of claim 1, further comprising means for monitoring the tension of warp threads and means for changing the speed of said rotating means in response to changes in said tension.
 23. The structure of claim 1, wherein said means for rotating comprises a plurality of synchronized transmissions having output elements arranged to rotate said collecting beams. 